Piston construction



Nov. 6 1923.

PIsToN CONSTRUCTION` Filed Aug. 25., 1921 gf. @@f

l k. l

TTORNEY.

Patented N ov. v6, 1923.

. UNITED STATES 1,472,893 PATENT OFFICE.

:PAUL GEIRHARID"l'ISJlLIlER,` 0F NEW YORK, N. Y., ASSIGNOR T0 RIN PISTON COM- `PANY, A CORPORATION OF DELAWARE.

.PIs'roN CONSTRUCTION.

Application led August 2'5, 1921. Serial No. 495,317.

To all 107mm t may concern? 'f- Be it known that I, PAUL G. TIsimR, a

citizen of the German Republic, residing at New York, in the county of New York, State otl New York, have invented certain new and useful Improvements in Piston Constructions; andl do herebydcclare the following to be a full, clear, and exact description of the invention, suchas will enable others skilled in the art to A'which it appertains to make and usel the same.

The patentto Paul G. Tismer No. 1,272,- 578, issued July 16, 1918, describes a ringless piston` an important point in the elimination of the piston rino' being that'there is maintained between the piston and the cylinder wall a continuous oil film. The maintenance of this continuous oil iilm is made possible by the elimination'of the piston rings and consequentelimination of their scraping action, and of course,` eliminates all friction due to piston rings. This oil film between the piston vof the cylinder wall does two things; it separates the piston from the cylinder wall so that there is no metalon-meta-l contact, but instead only metalon-oil contact, whereby friction is very much reduced; it acts as a lpacking or seal between the piston` `and cylinder, whereby a gas-tight lit is maintained at' alltimes` between these parts. Due to the fact that the explosion pressure is exerted only on the upper edge of an attenua-ted oil film, that the time element is short and that capillary attraction exists between'the oil and metal, the oil film or oil seal does not blow out, but is at all times effectively maintained.

The invention in this case relates t-o an improved piston construction of the ringless type which is light, strong, and easy to manufacture.

The vpiston shown in the Tismer patent is of the concave head type. vThe piston of this invention, however, is of the convex head type and is made in two parts; one part, the centrally disposed frame, comprises a convex head, a lower rim, and webs extending lengthwise of the piston and connected respectively to the said head 'and rim;

the other part, the cylindrical shell, is a cylinder of substantially uniform thickness, that engages with the frame only at its upper and lower edges; it is not provided with piston rings.

The mentioned webs have two particularly vimportant functions. They support ithe wrist'pin bearings, whereby there isno necessity of providing bosses on the interior of the shell for such bearings.. The presence of such bosses is particularly objectionable because the extra metal causes unequal eX-v pansion of the shell. The avoidance of unequal expansion'is an important feature ofl the Tisiner ringless pistons. `Uniforme):- pansion is attained by-making the shell of substantially uniform thickness throughout, so that it will expand uniformly in all directions and by supporting the wrist pin bearings on the lower frame, separate `*from the shell. The other important vfunction ofthe webs is to conduct heat away from the head of the piston; These webs are preferably made integral with the upper centralvpart of the piston whereit is hottest-and where there is need for cooling action. The eX- cess heat is Lconducted away through lthe. webs yand is 4radiated from their innerk andouter walls. f

i Other advantages and structural details will be apparent from the subsequentdescription. The drawings illustrate a pref ferr-ed emloodiment of the-invention, but it will, of course, be understood that. the inventionis not-limited to thespecitic structuraldetails shown but maybe carried out in other ways as defined within the scope of the appended claims. iVhile the described piston construction is particularly.applicable to a piston olf the iringlesstype,piston rings could be used,4 it desired. Y

In the drawings, inwhich corresponding reference 'characters indicate corresponding parts, Fig. l is avertical sectional View through one form of piston; Fig. 2 is a. section on the line 2 2 of Fig. l; and Fig. 3 is a view similar to Fig.A l, of another form of piston.

Referring now to. the drawings, the frame comprises a convex head 1, here shown as shaped substantially like the segmentl of a sphere. Longitudinally extending webs 2, preferably cast integral with the Ihead 1, support the wrist pin bearings 3, and continue downwardly to the rim 4, which may be integral with the webs. The outer part- Of the convex head l may be provided with an exteriorly threaded flange 5. The shell comprises a body portion 10 which is cylindrical and of substantially uniform thickness throughout and is `provided with upper and shell and the rirn'i.`

flanges 5 is a threaded one, while there is a sliding tit between the lower edge of the After the frame and shell are assembled, a hole 13 is drilled between the rims 4 and 12 in which a cotterl pin is put for preventing relative rotation of the shell and frame. A keying pin may be also used in hole 14 to preventl relative rotation of the two parts.

The piston shownl in Fig. 3 is very similar to that shown in Fig. 1, the main difference being that the head 15 is polygonal in shape rather than spherical and the general construction heavier. The heavier construction does away with the necessity of providing the flanges 11 and 12, shown in Fig. 1. In Figs. l and 3 the shells 10 are not provided 'with piston rings.

The pistons described are light, strong, and work with a minimum of friction, be-

' cause they ride at all times on a'film of oil n of such bearings.

` or other engine,

and because the scraping friction of the piston rings .is eliminated. The bearings for the wrist pin are supported entirely by the inner frame 'so that any expansion of the metal in the wrist pin or bearings has no effect on the shell. Therefore, there can be 4no distortion of the shell due to expansion Another advantage is that the head of the piston is coole-d by conduction through the longitudinally extending webs. Any expansion or contraction of webs takes place longitudinally of the piston and therefore has no tendency to cause the pis-V ton to seize.

Having thus claimz 1. In a piston described my invention. I

for` an internal combustion a centrally disposed frame including a convex head and longitudinally extending webs engaging the head at a point well above the lower point thereof, wrist pin bearings carried by the said webs, in combination with a cylindrical shell that engages with the frame at the 'upper and lower edges of said shell, said bearings being out of contact with said shell.

2. A ringless piston for an internal coinbustion Voi' other engine, comprising a centrally disposed frame including a convex head, longitudinally extending webs continuously converging toward the top ofsaid frame, wrist pin bearings carried by said webs, and a cylindrical shell, of substantially uniform thickness, that is not provided with piston rings, the shell being connected to the frame at its'upper and lower edges, said bearings being out of contact with said shell.

3. In a piston for an internal combustion or other engine, a centrally disposed frame including a convex head, a lower rim, longitudinally extending webs connectedto the top of the head and to the lower rim, respectively, wrist pin bearings carried by the said webs, in combination with a cylindrical shell that engages at its upper and lower ends with the outer part of the convex head, and said lower rim, respectively, said bearings being outl of 'Contact with said shell. x

4f. In a piston for an internal combustion or other engine, a centrally disposed frame including a convex head, a lower rim, longitudinally extending webs connected to the v 

